[PATCH v6 0/3] tests/qtest/libqos: add DMA support for writing and reading fw_cfg files

[PATCH v6 0/3] tests/qtest/libqos: add DMA support for writing and reading fw_cfg files

[Ani Sinha]

This patchset enables DMA interface support for writing fw-cfg files in
libqtest. The first patch is just a code refactoring so that fw-cfg
directory parsing can be part of a separate helper function.
The second patch is the actual patch that introduces two new apis for
writing and reading fw-cfg files using DMA interface. The apis are
tested by writing a new basic qtest for vmcoreinfo device in patch 3.

$ MALLOC_PERTURB_=255  QTEST_QEMU_BINARY=./qemu-system-x86_64  /workspace/qemu-ani/build/tests/qtest/vmcoreinfo-test
TAP version 13
# random seed: R02S33ea0ae4568aae69a6191a97e6ea37fc
1..1
# Start of x86_64 tests
# Start of vmcoreinfo tests
# starting QEMU: exec ./qemu-system-x86_64 -qtest unix:/tmp/qtest-267380.sock -qtest-log /dev/null -chardev socket,path=/tmp/qtest-267380.qmp,id=char0 -mon chardev=char0,mode=control -display none -audio none -device vmcoreinfo -accel qtest
ok 1 /x86_64/vmcoreinfo/basic-write
# End of vmcoreinfo tests
# End of x86_64 tests

CI pipeline is green with this patch series: https://gitlab.com/anisinha/qemu/-/pipelines/1629670893

checkpatch is clean:

$ ./scripts/checkpatch.pl patches-v6/*
Checking patches-v6/v6-0000-cover-letter.patch...
total: 0 errors, 0 warnings, 0 lines checked

patches-v6/v6-0000-cover-letter.patch has no obvious style problems and is ready for submission.
Checking patches-v6/v6-0001-libqos-fw_cfg-refactor-file-directory-iteraton-to.patch...
total: 0 errors, 0 warnings, 80 lines checked

patches-v6/v6-0001-libqos-fw_cfg-refactor-file-directory-iteraton-to.patch has no obvious style problems and is ready for submission.
Checking patches-v6/v6-0002-tests-qtest-libqos-add-DMA-support-for-writing-an.patch...
total: 0 errors, 0 warnings, 175 lines checked

patches-v6/v6-0002-tests-qtest-libqos-add-DMA-support-for-writing-an.patch has no obvious style problems and is ready for submission.
Checking patches-v6/v6-0003-tests-qtest-vmcoreinfo-add-a-unit-test-to-exerciz.patch...
total: 0 errors, 0 warnings, 111 lines checked

patches-v6/v6-0003-tests-qtest-vmcoreinfo-add-a-unit-test-to-exerciz.patch has no obvious style problems and is ready for submission.


cc: kraxel@redhat.com
cc: farosas@suse.de
cc: lvivier@redhat.com
cc: pbonzini@redhat.com
cc: armbru@redhat.com
cc: philmd@linaro.org
cc: berrange@redhat.com
cc: qemu-devel@nongnu.org
cc: farosas@suse.de

changelog:
v3: first working version of the patch.
v4: refactoring without any new changes put into a new patch.
v5: a new qtest added to exercize the two new write and read apis.
v6: minor, coding style changed to standard qemu func prototype style - 
phil's sugestion. tags added and rebased to the latest.
  
all along, other review feedbacks has been taken into account.

Ani Sinha (3):
  libqos/fw_cfg: refactor file directory iteraton to make it more
    reusable
  tests/qtest/libqos: add DMA support for writing and reading fw_cfg
    files
  tests/qtest/vmcoreinfo: add a unit test to exercize basic vmcoreinfo
    function

 MAINTAINERS                   |   2 +
 tests/qtest/libqos/fw_cfg.c   | 202 ++++++++++++++++++++++++++++++----
 tests/qtest/libqos/fw_cfg.h   |   6 +-
 tests/qtest/meson.build       |   1 +
 tests/qtest/vmcoreinfo-test.c |  90 +++++++++++++++
 5 files changed, 277 insertions(+), 24 deletions(-)
 create mode 100644 tests/qtest/vmcoreinfo-test.c

-- 
2.45.2

[PATCH v6 1/3] libqos/fw_cfg: refactor file directory iteraton to make it more reusable

[Ani Sinha]

fw-cfg file directory iteration code can be used by other functions that may
want to implement fw-cfg file operations. Refactor it into a smaller helper
so that it can be reused.

No functional change.

Signed-off-by: Ani Sinha <anisinha@redhat.com>
Reviewed-by:  Fabiano Rosas <farosas@suse.de>
---
 tests/qtest/libqos/fw_cfg.c | 63 +++++++++++++++++++++++--------------
 1 file changed, 40 insertions(+), 23 deletions(-)

diff --git a/tests/qtest/libqos/fw_cfg.c b/tests/qtest/libqos/fw_cfg.c
index 89f053ccac..22435873d9 100644
--- a/tests/qtest/libqos/fw_cfg.c
+++ b/tests/qtest/libqos/fw_cfg.c
@@ -60,6 +60,37 @@ static void mm_fw_cfg_select(QFWCFG *fw_cfg, uint16_t key)
     qtest_writew(fw_cfg->qts, fw_cfg->base, key);
 }
 
+static bool find_pdir_entry(QFWCFG *fw_cfg, const char *filename,
+                            uint16_t *sel, uint32_t *size)
+{
+    g_autofree unsigned char *filesbuf = NULL;
+    uint32_t count;
+    size_t dsize;
+    FWCfgFile *pdir_entry;
+    uint32_t i;
+    bool found = false;
+
+    *size = 0;
+    *sel = 0;
+
+    qfw_cfg_get(fw_cfg, FW_CFG_FILE_DIR, &count, sizeof(count));
+    count = be32_to_cpu(count);
+    dsize = sizeof(uint32_t) + count * sizeof(struct fw_cfg_file);
+    filesbuf = g_malloc(dsize);
+    qfw_cfg_get(fw_cfg, FW_CFG_FILE_DIR, filesbuf, dsize);
+    pdir_entry = (FWCfgFile *)(filesbuf + sizeof(uint32_t));
+    for (i = 0; i < count; ++i, ++pdir_entry) {
+        if (!strcmp(pdir_entry->name, filename)) {
+            *size = be32_to_cpu(pdir_entry->size);
+            *sel = be16_to_cpu(pdir_entry->select);
+            found = true;
+            break;
+        }
+    }
+
+    return found;
+}
+
 /*
  * The caller need check the return value. When the return value is
  * nonzero, it means that some bytes have been transferred.
@@ -73,34 +104,20 @@ static void mm_fw_cfg_select(QFWCFG *fw_cfg, uint16_t key)
  * populated, it has received only a starting slice of the fw_cfg file.
  */
 size_t qfw_cfg_get_file(QFWCFG *fw_cfg, const char *filename,
-                      void *data, size_t buflen)
+                        void *data, size_t buflen)
 {
-    uint32_t count;
-    uint32_t i;
-    unsigned char *filesbuf = NULL;
-    size_t dsize;
-    FWCfgFile *pdir_entry;
     size_t filesize = 0;
+    uint32_t len;
+    uint16_t sel;
 
-    qfw_cfg_get(fw_cfg, FW_CFG_FILE_DIR, &count, sizeof(count));
-    count = be32_to_cpu(count);
-    dsize = sizeof(uint32_t) + count * sizeof(struct fw_cfg_file);
-    filesbuf = g_malloc(dsize);
-    qfw_cfg_get(fw_cfg, FW_CFG_FILE_DIR, filesbuf, dsize);
-    pdir_entry = (FWCfgFile *)(filesbuf + sizeof(uint32_t));
-    for (i = 0; i < count; ++i, ++pdir_entry) {
-        if (!strcmp(pdir_entry->name, filename)) {
-            uint32_t len = be32_to_cpu(pdir_entry->size);
-            uint16_t sel = be16_to_cpu(pdir_entry->select);
-            filesize = len;
-            if (len > buflen) {
-                len = buflen;
-            }
-            qfw_cfg_get(fw_cfg, sel, data, len);
-            break;
+    if (find_pdir_entry(fw_cfg, filename, &sel, &len)) {
+        filesize = len;
+        if (len > buflen) {
+            len = buflen;
         }
+        qfw_cfg_get(fw_cfg, sel, data, len);
     }
-    g_free(filesbuf);
+
     return filesize;
 }
 
-- 
2.45.2

[PATCH v6 2/3] tests/qtest/libqos: add DMA support for writing and reading fw_cfg files

[Ani Sinha]

At present, the libqos/fw_cfg.c library does not support the modern DMA
interface which is required to write to the fw_cfg files. It only uses the IO
interface. Implement read and write methods based on DMA. This will enable
developers to add tests that writes to the fw_cfg file(s). The structure of
the code is taken from edk2 fw_cfg implementation. It has been tested by
writing a qtest that writes to a fw_cfg file.

Signed-off-by: Ani Sinha <anisinha@redhat.com>
---
 tests/qtest/libqos/fw_cfg.c | 139 ++++++++++++++++++++++++++++++++++++
 tests/qtest/libqos/fw_cfg.h |   6 +-
 2 files changed, 144 insertions(+), 1 deletion(-)

diff --git a/tests/qtest/libqos/fw_cfg.c b/tests/qtest/libqos/fw_cfg.c
index 22435873d9..0ab3959171 100644
--- a/tests/qtest/libqos/fw_cfg.c
+++ b/tests/qtest/libqos/fw_cfg.c
@@ -14,6 +14,8 @@
 
 #include "qemu/osdep.h"
 #include "fw_cfg.h"
+#include "malloc-pc.h"
+#include "libqos-malloc.h"
 #include "../libqtest.h"
 #include "qemu/bswap.h"
 #include "hw/nvram/fw_cfg.h"
@@ -60,6 +62,60 @@ static void mm_fw_cfg_select(QFWCFG *fw_cfg, uint16_t key)
     qtest_writew(fw_cfg->qts, fw_cfg->base, key);
 }
 
+static void qfw_cfg_dma_transfer(QFWCFG *fw_cfg, QOSState *qs, void *address,
+                                 uint32_t length, uint32_t control)
+{
+    FWCfgDmaAccess access;
+    uint32_t addr;
+    uint64_t guest_access_addr;
+    uint64_t gaddr;
+
+    /* create a data buffer in guest memory */
+    gaddr = guest_alloc(&qs->alloc, length);
+
+    if (control & FW_CFG_DMA_CTL_WRITE) {
+        qtest_bufwrite(fw_cfg->qts, gaddr, address, length);
+    }
+    access.address = cpu_to_be64(gaddr);
+    access.length = cpu_to_be32(length);
+    access.control = cpu_to_be32(control);
+
+    /* now create a separate buffer in guest memory for 'access' */
+    guest_access_addr = guest_alloc(&qs->alloc, sizeof(access));
+    qtest_bufwrite(fw_cfg->qts, guest_access_addr, &access, sizeof(access));
+
+    /* write lower 32 bits of address */
+    addr = cpu_to_be32((uint32_t)(uintptr_t)guest_access_addr);
+    qtest_outl(fw_cfg->qts, fw_cfg->base + 8, addr);
+
+    /* write upper 32 bits of address */
+    addr = cpu_to_be32((uint32_t)(uintptr_t)(guest_access_addr >> 32));
+    qtest_outl(fw_cfg->qts, fw_cfg->base + 4, addr);
+
+    g_assert(!(be32_to_cpu(access.control) & FW_CFG_DMA_CTL_ERROR));
+
+    if (control & FW_CFG_DMA_CTL_READ) {
+        qtest_bufread(fw_cfg->qts, gaddr, address, length);
+    }
+
+    guest_free(&qs->alloc, guest_access_addr);
+    guest_free(&qs->alloc, gaddr);
+}
+
+static void qfw_cfg_write_entry(QFWCFG *fw_cfg, QOSState *qs, uint16_t key,
+                                void *buf, uint32_t len)
+{
+    qfw_cfg_select(fw_cfg, key);
+    qfw_cfg_dma_transfer(fw_cfg, qs, buf, len, FW_CFG_DMA_CTL_WRITE);
+}
+
+static void qfw_cfg_read_entry(QFWCFG *fw_cfg, QOSState *qs, uint16_t key,
+                               void *buf, uint32_t len)
+{
+    qfw_cfg_select(fw_cfg, key);
+    qfw_cfg_dma_transfer(fw_cfg, qs, buf, len, FW_CFG_DMA_CTL_READ);
+}
+
 static bool find_pdir_entry(QFWCFG *fw_cfg, const char *filename,
                             uint16_t *sel, uint32_t *size)
 {
@@ -121,6 +177,89 @@ size_t qfw_cfg_get_file(QFWCFG *fw_cfg, const char *filename,
     return filesize;
 }
 
+/*
+ * The caller need check the return value. When the return value is
+ * nonzero, it means that some bytes have been transferred.
+ *
+ * If the fw_cfg file in question is smaller than the allocated & passed-in
+ * buffer, then the first len bytes were read.
+ *
+ * If the fw_cfg file in question is larger than the passed-in
+ * buffer, then the return value explains how much was actually read.
+ *
+ * It is illegal to call this function if fw_cfg does not support DMA
+ * interface. The caller should ensure that DMA is supported before
+ * calling this function.
+ *
+ * Passed QOSState pointer qs must be initialized. qs->alloc must also be
+ * properly initialized.
+ */
+size_t qfw_cfg_read_file(QFWCFG *fw_cfg, QOSState *qs, const char *filename,
+                         void *data, size_t buflen)
+{
+    uint32_t len = 0;
+    uint16_t sel;
+    uint32_t id;
+
+    g_assert(qs);
+    g_assert(filename);
+    g_assert(data);
+    g_assert(buflen);
+    /* check if DMA is supported since we use DMA for read */
+    id = qfw_cfg_get_u32(fw_cfg, FW_CFG_ID);
+    g_assert(id & FW_CFG_VERSION_DMA);
+
+    if (find_pdir_entry(fw_cfg, filename, &sel, &len)) {
+        if (len > buflen) {
+            len = buflen;
+        }
+        qfw_cfg_read_entry(fw_cfg, qs, sel, data, len);
+    }
+
+    return len;
+}
+
+/*
+ * The caller need check the return value. When the return value is
+ * nonzero, it means that some bytes have been transferred.
+ *
+ * If the fw_cfg file in question is smaller than the allocated & passed-in
+ * buffer, then the buffer has been partially written.
+ *
+ * If the fw_cfg file in question is larger than the passed-in
+ * buffer, then the return value explains how much was actually written.
+ *
+ * It is illegal to call this function if fw_cfg does not support DMA
+ * interface. The caller should ensure that DMA is supported before
+ * calling this function.
+ *
+ * Passed QOSState pointer qs must be initialized. qs->alloc must also be
+ * properly initialized.
+ */
+size_t qfw_cfg_write_file(QFWCFG *fw_cfg, QOSState *qs, const char *filename,
+                          void *data, size_t buflen)
+{
+    uint32_t len = 0;
+    uint16_t sel;
+    uint32_t id;
+
+    g_assert(qs);
+    g_assert(filename);
+    g_assert(data);
+    g_assert(buflen);
+    /* write operation is only valid if DMA is supported */
+    id = qfw_cfg_get_u32(fw_cfg, FW_CFG_ID);
+    g_assert(id & FW_CFG_VERSION_DMA);
+
+    if (find_pdir_entry(fw_cfg, filename, &sel, &len)) {
+        if (len > buflen) {
+            len = buflen;
+        }
+        qfw_cfg_write_entry(fw_cfg, qs, sel, data, len);
+    }
+    return len;
+}
+
 static void mm_fw_cfg_read(QFWCFG *fw_cfg, void *data, size_t len)
 {
     uint8_t *ptr = data;
diff --git a/tests/qtest/libqos/fw_cfg.h b/tests/qtest/libqos/fw_cfg.h
index b0456a15df..6d6ff09725 100644
--- a/tests/qtest/libqos/fw_cfg.h
+++ b/tests/qtest/libqos/fw_cfg.h
@@ -14,6 +14,7 @@
 #define LIBQOS_FW_CFG_H
 
 #include "../libqtest.h"
+#include "libqos.h"
 
 typedef struct QFWCFG QFWCFG;
 
@@ -33,7 +34,10 @@ uint32_t qfw_cfg_get_u32(QFWCFG *fw_cfg, uint16_t key);
 uint64_t qfw_cfg_get_u64(QFWCFG *fw_cfg, uint16_t key);
 size_t qfw_cfg_get_file(QFWCFG *fw_cfg, const char *filename,
                         void *data, size_t buflen);
-
+size_t qfw_cfg_write_file(QFWCFG *fw_cfg, QOSState *qs, const char *filename,
+                          void *data, size_t buflen);
+size_t qfw_cfg_read_file(QFWCFG *fw_cfg, QOSState *qs, const char *filename,
+                         void *data, size_t buflen);
 QFWCFG *mm_fw_cfg_init(QTestState *qts, uint64_t base);
 void mm_fw_cfg_uninit(QFWCFG *fw_cfg);
 QFWCFG *io_fw_cfg_init(QTestState *qts, uint16_t base);
-- 
2.45.2

[PATCH v6 3/3] tests/qtest/vmcoreinfo: add a unit test to exercize basic vmcoreinfo function

[Ani Sinha]

A new qtest is written that exercizes the fw-cfg DMA based read and write ops
to write values into vmcoreinfo fw-cfg file and read them back and verify that
they are the same.

Signed-off-by: Ani Sinha <anisinha@redhat.com>
---
 MAINTAINERS                   |  2 +
 tests/qtest/meson.build       |  1 +
 tests/qtest/vmcoreinfo-test.c | 90 +++++++++++++++++++++++++++++++++++
 3 files changed, 93 insertions(+)
 create mode 100644 tests/qtest/vmcoreinfo-test.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 846b81e3ec..57167c3c73 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3016,6 +3016,7 @@ F: include/system/device_tree.h
 Dump
 S: Supported
 M: Marc-André Lureau <marcandre.lureau@redhat.com>
+R: Ani Sinha <anisinha@redhat.com>
 F: dump/
 F: hw/misc/vmcoreinfo.c
 F: include/hw/misc/vmcoreinfo.h
@@ -3026,6 +3027,7 @@ F: qapi/dump.json
 F: scripts/dump-guest-memory.py
 F: stubs/dump.c
 F: docs/specs/vmcoreinfo.rst
+F: tests/qtest/vmcoreinfo-test.c
 
 Error reporting
 M: Markus Armbruster <armbru@redhat.com>
diff --git a/tests/qtest/meson.build b/tests/qtest/meson.build
index 94b28e5a53..fc669336a6 100644
--- a/tests/qtest/meson.build
+++ b/tests/qtest/meson.build
@@ -57,6 +57,7 @@ qtests_i386 = \
   (config_all_devices.has_key('CONFIG_AHCI_ICH9') ? ['tco-test'] : []) +                    \
   (config_all_devices.has_key('CONFIG_FDC_ISA') ? ['fdc-test'] : []) +                      \
   (config_all_devices.has_key('CONFIG_I440FX') ? ['fw_cfg-test'] : []) +                    \
+  (config_all_devices.has_key('CONFIG_FW_CFG_DMA') ? ['vmcoreinfo-test'] : []) +            \
   (config_all_devices.has_key('CONFIG_I440FX') ? ['i440fx-test'] : []) +                    \
   (config_all_devices.has_key('CONFIG_I440FX') ? ['ide-test'] : []) +                       \
   (config_all_devices.has_key('CONFIG_I440FX') ? ['numa-test'] : []) +                      \
diff --git a/tests/qtest/vmcoreinfo-test.c b/tests/qtest/vmcoreinfo-test.c
new file mode 100644
index 0000000000..dcf3b5ae05
--- /dev/null
+++ b/tests/qtest/vmcoreinfo-test.c
@@ -0,0 +1,90 @@
+/*
+ * qtest vmcoreinfo test case
+ *
+ * Copyright Red Hat. 2025.
+ *
+ * Authors:
+ *  Ani Sinha   <anisinha@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/units.h"
+#include "libqos/libqos-pc.h"
+#include "libqtest.h"
+#include "standard-headers/linux/qemu_fw_cfg.h"
+#include "libqos/fw_cfg.h"
+#include "qemu/bswap.h"
+#include "hw/misc/vmcoreinfo.h"
+
+static void test_vmcoreinfo_write_basic(void)
+{
+    QFWCFG *fw_cfg;
+    QOSState *qs;
+    FWCfgVMCoreInfo info;
+    size_t filesize;
+    uint16_t guest_format;
+    uint16_t host_format;
+    uint32_t size;
+    uint64_t paddr;
+
+    qs = qtest_pc_boot("-device vmcoreinfo");
+    fw_cfg = pc_fw_cfg_init(qs->qts);
+
+    memset(&info, 0 , sizeof(info));
+    /* read vmcoreinfo and read back the host format */
+    filesize = qfw_cfg_read_file(fw_cfg, qs, FW_CFG_VMCOREINFO_FILENAME,
+                                &info, sizeof(info));
+    g_assert_cmpint(filesize, ==, sizeof(info));
+
+    host_format = le16_to_cpu(info.host_format);
+    g_assert_cmpint(host_format, ==, FW_CFG_VMCOREINFO_FORMAT_ELF);
+
+    memset(&info, 0 , sizeof(info));
+    info.guest_format = cpu_to_le16(FW_CFG_VMCOREINFO_FORMAT_ELF);
+    info.size = cpu_to_le32(1 * MiB);
+    info.paddr = cpu_to_le64(0xffffff00);
+    info.host_format = cpu_to_le16(host_format);
+
+    /* write the values to the host */
+    filesize = qfw_cfg_write_file(fw_cfg, qs, FW_CFG_VMCOREINFO_FILENAME,
+                                  &info, sizeof(info));
+    g_assert_cmpint(filesize, ==, sizeof(info));
+
+    memset(&info, 0 , sizeof(info));
+
+    /* now read back the values we wrote and compare that they are the same */
+    filesize = qfw_cfg_read_file(fw_cfg, qs, FW_CFG_VMCOREINFO_FILENAME,
+                                &info, sizeof(info));
+    g_assert_cmpint(filesize, ==, sizeof(info));
+
+    size = le32_to_cpu(info.size);
+    paddr = le64_to_cpu(info.paddr);
+    guest_format = le16_to_cpu(info.guest_format);
+
+    g_assert_cmpint(size, ==, 1 * MiB);
+    g_assert_cmpint(paddr, ==, 0xffffff00);
+    g_assert_cmpint(guest_format, ==, FW_CFG_VMCOREINFO_FORMAT_ELF);
+
+    pc_fw_cfg_uninit(fw_cfg);
+    qtest_shutdown(qs);
+}
+
+int main(int argc, char **argv)
+{
+    const char *arch = qtest_get_arch();
+
+    g_test_init(&argc, &argv, NULL);
+
+    if (strcmp(arch, "i386") && strcmp(arch, "x86_64")) {
+        /* skip for non-x86 */
+        exit(EXIT_SUCCESS);
+    }
+
+    qtest_add_func("vmcoreinfo/basic-write",
+                   test_vmcoreinfo_write_basic);
+
+    return g_test_run();
+}
-- 
2.45.2

Re: [PATCH v6 2/3] tests/qtest/libqos: add DMA support for writing and reading fw_cfg files

[Ani Sinha]

On Mon, Jan 20, 2025 at 10:09 AM Ani Sinha <anisinha@redhat.com> wrote:
>
> At present, the libqos/fw_cfg.c library does not support the modern DMA
> interface which is required to write to the fw_cfg files. It only uses the IO
> interface. Implement read and write methods based on DMA. This will enable
> developers to add tests that writes to the fw_cfg file(s). The structure of
> the code is taken from edk2 fw_cfg implementation. It has been tested by
> writing a qtest that writes to a fw_cfg file.
>
> Signed-off-by: Ani Sinha <anisinha@redhat.com>

Final ping on this patch series ...

> ---
>  tests/qtest/libqos/fw_cfg.c | 139 ++++++++++++++++++++++++++++++++++++
>  tests/qtest/libqos/fw_cfg.h |   6 +-
>  2 files changed, 144 insertions(+), 1 deletion(-)
>
> diff --git a/tests/qtest/libqos/fw_cfg.c b/tests/qtest/libqos/fw_cfg.c
> index 22435873d9..0ab3959171 100644
> --- a/tests/qtest/libqos/fw_cfg.c
> +++ b/tests/qtest/libqos/fw_cfg.c
> @@ -14,6 +14,8 @@
>
>  #include "qemu/osdep.h"
>  #include "fw_cfg.h"
> +#include "malloc-pc.h"
> +#include "libqos-malloc.h"
>  #include "../libqtest.h"
>  #include "qemu/bswap.h"
>  #include "hw/nvram/fw_cfg.h"
> @@ -60,6 +62,60 @@ static void mm_fw_cfg_select(QFWCFG *fw_cfg, uint16_t key)
>      qtest_writew(fw_cfg->qts, fw_cfg->base, key);
>  }
>
> +static void qfw_cfg_dma_transfer(QFWCFG *fw_cfg, QOSState *qs, void *address,
> +                                 uint32_t length, uint32_t control)
> +{
> +    FWCfgDmaAccess access;
> +    uint32_t addr;
> +    uint64_t guest_access_addr;
> +    uint64_t gaddr;
> +
> +    /* create a data buffer in guest memory */
> +    gaddr = guest_alloc(&qs->alloc, length);
> +
> +    if (control & FW_CFG_DMA_CTL_WRITE) {
> +        qtest_bufwrite(fw_cfg->qts, gaddr, address, length);
> +    }
> +    access.address = cpu_to_be64(gaddr);
> +    access.length = cpu_to_be32(length);
> +    access.control = cpu_to_be32(control);
> +
> +    /* now create a separate buffer in guest memory for 'access' */
> +    guest_access_addr = guest_alloc(&qs->alloc, sizeof(access));
> +    qtest_bufwrite(fw_cfg->qts, guest_access_addr, &access, sizeof(access));
> +
> +    /* write lower 32 bits of address */
> +    addr = cpu_to_be32((uint32_t)(uintptr_t)guest_access_addr);
> +    qtest_outl(fw_cfg->qts, fw_cfg->base + 8, addr);
> +
> +    /* write upper 32 bits of address */
> +    addr = cpu_to_be32((uint32_t)(uintptr_t)(guest_access_addr >> 32));
> +    qtest_outl(fw_cfg->qts, fw_cfg->base + 4, addr);
> +
> +    g_assert(!(be32_to_cpu(access.control) & FW_CFG_DMA_CTL_ERROR));
> +
> +    if (control & FW_CFG_DMA_CTL_READ) {
> +        qtest_bufread(fw_cfg->qts, gaddr, address, length);
> +    }
> +
> +    guest_free(&qs->alloc, guest_access_addr);
> +    guest_free(&qs->alloc, gaddr);
> +}
> +
> +static void qfw_cfg_write_entry(QFWCFG *fw_cfg, QOSState *qs, uint16_t key,
> +                                void *buf, uint32_t len)
> +{
> +    qfw_cfg_select(fw_cfg, key);
> +    qfw_cfg_dma_transfer(fw_cfg, qs, buf, len, FW_CFG_DMA_CTL_WRITE);
> +}
> +
> +static void qfw_cfg_read_entry(QFWCFG *fw_cfg, QOSState *qs, uint16_t key,
> +                               void *buf, uint32_t len)
> +{
> +    qfw_cfg_select(fw_cfg, key);
> +    qfw_cfg_dma_transfer(fw_cfg, qs, buf, len, FW_CFG_DMA_CTL_READ);
> +}
> +
>  static bool find_pdir_entry(QFWCFG *fw_cfg, const char *filename,
>                              uint16_t *sel, uint32_t *size)
>  {
> @@ -121,6 +177,89 @@ size_t qfw_cfg_get_file(QFWCFG *fw_cfg, const char *filename,
>      return filesize;
>  }
>
> +/*
> + * The caller need check the return value. When the return value is
> + * nonzero, it means that some bytes have been transferred.
> + *
> + * If the fw_cfg file in question is smaller than the allocated & passed-in
> + * buffer, then the first len bytes were read.
> + *
> + * If the fw_cfg file in question is larger than the passed-in
> + * buffer, then the return value explains how much was actually read.
> + *
> + * It is illegal to call this function if fw_cfg does not support DMA
> + * interface. The caller should ensure that DMA is supported before
> + * calling this function.
> + *
> + * Passed QOSState pointer qs must be initialized. qs->alloc must also be
> + * properly initialized.
> + */
> +size_t qfw_cfg_read_file(QFWCFG *fw_cfg, QOSState *qs, const char *filename,
> +                         void *data, size_t buflen)
> +{
> +    uint32_t len = 0;
> +    uint16_t sel;
> +    uint32_t id;
> +
> +    g_assert(qs);
> +    g_assert(filename);
> +    g_assert(data);
> +    g_assert(buflen);
> +    /* check if DMA is supported since we use DMA for read */
> +    id = qfw_cfg_get_u32(fw_cfg, FW_CFG_ID);
> +    g_assert(id & FW_CFG_VERSION_DMA);
> +
> +    if (find_pdir_entry(fw_cfg, filename, &sel, &len)) {
> +        if (len > buflen) {
> +            len = buflen;
> +        }
> +        qfw_cfg_read_entry(fw_cfg, qs, sel, data, len);
> +    }
> +
> +    return len;
> +}
> +
> +/*
> + * The caller need check the return value. When the return value is
> + * nonzero, it means that some bytes have been transferred.
> + *
> + * If the fw_cfg file in question is smaller than the allocated & passed-in
> + * buffer, then the buffer has been partially written.
> + *
> + * If the fw_cfg file in question is larger than the passed-in
> + * buffer, then the return value explains how much was actually written.
> + *
> + * It is illegal to call this function if fw_cfg does not support DMA
> + * interface. The caller should ensure that DMA is supported before
> + * calling this function.
> + *
> + * Passed QOSState pointer qs must be initialized. qs->alloc must also be
> + * properly initialized.
> + */
> +size_t qfw_cfg_write_file(QFWCFG *fw_cfg, QOSState *qs, const char *filename,
> +                          void *data, size_t buflen)
> +{
> +    uint32_t len = 0;
> +    uint16_t sel;
> +    uint32_t id;
> +
> +    g_assert(qs);
> +    g_assert(filename);
> +    g_assert(data);
> +    g_assert(buflen);
> +    /* write operation is only valid if DMA is supported */
> +    id = qfw_cfg_get_u32(fw_cfg, FW_CFG_ID);
> +    g_assert(id & FW_CFG_VERSION_DMA);
> +
> +    if (find_pdir_entry(fw_cfg, filename, &sel, &len)) {
> +        if (len > buflen) {
> +            len = buflen;
> +        }
> +        qfw_cfg_write_entry(fw_cfg, qs, sel, data, len);
> +    }
> +    return len;
> +}
> +
>  static void mm_fw_cfg_read(QFWCFG *fw_cfg, void *data, size_t len)
>  {
>      uint8_t *ptr = data;
> diff --git a/tests/qtest/libqos/fw_cfg.h b/tests/qtest/libqos/fw_cfg.h
> index b0456a15df..6d6ff09725 100644
> --- a/tests/qtest/libqos/fw_cfg.h
> +++ b/tests/qtest/libqos/fw_cfg.h
> @@ -14,6 +14,7 @@
>  #define LIBQOS_FW_CFG_H
>
>  #include "../libqtest.h"
> +#include "libqos.h"
>
>  typedef struct QFWCFG QFWCFG;
>
> @@ -33,7 +34,10 @@ uint32_t qfw_cfg_get_u32(QFWCFG *fw_cfg, uint16_t key);
>  uint64_t qfw_cfg_get_u64(QFWCFG *fw_cfg, uint16_t key);
>  size_t qfw_cfg_get_file(QFWCFG *fw_cfg, const char *filename,
>                          void *data, size_t buflen);
> -
> +size_t qfw_cfg_write_file(QFWCFG *fw_cfg, QOSState *qs, const char *filename,
> +                          void *data, size_t buflen);
> +size_t qfw_cfg_read_file(QFWCFG *fw_cfg, QOSState *qs, const char *filename,
> +                         void *data, size_t buflen);
>  QFWCFG *mm_fw_cfg_init(QTestState *qts, uint64_t base);
>  void mm_fw_cfg_uninit(QFWCFG *fw_cfg);
>  QFWCFG *io_fw_cfg_init(QTestState *qts, uint16_t base);
> --
> 2.45.2
>

Re: [PATCH v6 3/3] tests/qtest/vmcoreinfo: add a unit test to exercize basic vmcoreinfo function

[Ani Sinha]

On Mon, Jan 20, 2025 at 10:09 AM Ani Sinha <anisinha@redhat.com> wrote:
>
> A new qtest is written that exercizes the fw-cfg DMA based read and write ops
> to write values into vmcoreinfo fw-cfg file and read them back and verify that
> they are the same.
>
> Signed-off-by: Ani Sinha <anisinha@redhat.com>

Final ping on this patch.

> ---
>  MAINTAINERS                   |  2 +
>  tests/qtest/meson.build       |  1 +
>  tests/qtest/vmcoreinfo-test.c | 90 +++++++++++++++++++++++++++++++++++
>  3 files changed, 93 insertions(+)
>  create mode 100644 tests/qtest/vmcoreinfo-test.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 846b81e3ec..57167c3c73 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3016,6 +3016,7 @@ F: include/system/device_tree.h
>  Dump
>  S: Supported
>  M: Marc-André Lureau <marcandre.lureau@redhat.com>
> +R: Ani Sinha <anisinha@redhat.com>
>  F: dump/
>  F: hw/misc/vmcoreinfo.c
>  F: include/hw/misc/vmcoreinfo.h
> @@ -3026,6 +3027,7 @@ F: qapi/dump.json
>  F: scripts/dump-guest-memory.py
>  F: stubs/dump.c
>  F: docs/specs/vmcoreinfo.rst
> +F: tests/qtest/vmcoreinfo-test.c
>
>  Error reporting
>  M: Markus Armbruster <armbru@redhat.com>
> diff --git a/tests/qtest/meson.build b/tests/qtest/meson.build
> index 94b28e5a53..fc669336a6 100644
> --- a/tests/qtest/meson.build
> +++ b/tests/qtest/meson.build
> @@ -57,6 +57,7 @@ qtests_i386 = \
>    (config_all_devices.has_key('CONFIG_AHCI_ICH9') ? ['tco-test'] : []) +                    \
>    (config_all_devices.has_key('CONFIG_FDC_ISA') ? ['fdc-test'] : []) +                      \
>    (config_all_devices.has_key('CONFIG_I440FX') ? ['fw_cfg-test'] : []) +                    \
> +  (config_all_devices.has_key('CONFIG_FW_CFG_DMA') ? ['vmcoreinfo-test'] : []) +            \
>    (config_all_devices.has_key('CONFIG_I440FX') ? ['i440fx-test'] : []) +                    \
>    (config_all_devices.has_key('CONFIG_I440FX') ? ['ide-test'] : []) +                       \
>    (config_all_devices.has_key('CONFIG_I440FX') ? ['numa-test'] : []) +                      \
> diff --git a/tests/qtest/vmcoreinfo-test.c b/tests/qtest/vmcoreinfo-test.c
> new file mode 100644
> index 0000000000..dcf3b5ae05
> --- /dev/null
> +++ b/tests/qtest/vmcoreinfo-test.c
> @@ -0,0 +1,90 @@
> +/*
> + * qtest vmcoreinfo test case
> + *
> + * Copyright Red Hat. 2025.
> + *
> + * Authors:
> + *  Ani Sinha   <anisinha@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qemu/units.h"
> +#include "libqos/libqos-pc.h"
> +#include "libqtest.h"
> +#include "standard-headers/linux/qemu_fw_cfg.h"
> +#include "libqos/fw_cfg.h"
> +#include "qemu/bswap.h"
> +#include "hw/misc/vmcoreinfo.h"
> +
> +static void test_vmcoreinfo_write_basic(void)
> +{
> +    QFWCFG *fw_cfg;
> +    QOSState *qs;
> +    FWCfgVMCoreInfo info;
> +    size_t filesize;
> +    uint16_t guest_format;
> +    uint16_t host_format;
> +    uint32_t size;
> +    uint64_t paddr;
> +
> +    qs = qtest_pc_boot("-device vmcoreinfo");
> +    fw_cfg = pc_fw_cfg_init(qs->qts);
> +
> +    memset(&info, 0 , sizeof(info));
> +    /* read vmcoreinfo and read back the host format */
> +    filesize = qfw_cfg_read_file(fw_cfg, qs, FW_CFG_VMCOREINFO_FILENAME,
> +                                &info, sizeof(info));
> +    g_assert_cmpint(filesize, ==, sizeof(info));
> +
> +    host_format = le16_to_cpu(info.host_format);
> +    g_assert_cmpint(host_format, ==, FW_CFG_VMCOREINFO_FORMAT_ELF);
> +
> +    memset(&info, 0 , sizeof(info));
> +    info.guest_format = cpu_to_le16(FW_CFG_VMCOREINFO_FORMAT_ELF);
> +    info.size = cpu_to_le32(1 * MiB);
> +    info.paddr = cpu_to_le64(0xffffff00);
> +    info.host_format = cpu_to_le16(host_format);
> +
> +    /* write the values to the host */
> +    filesize = qfw_cfg_write_file(fw_cfg, qs, FW_CFG_VMCOREINFO_FILENAME,
> +                                  &info, sizeof(info));
> +    g_assert_cmpint(filesize, ==, sizeof(info));
> +
> +    memset(&info, 0 , sizeof(info));
> +
> +    /* now read back the values we wrote and compare that they are the same */
> +    filesize = qfw_cfg_read_file(fw_cfg, qs, FW_CFG_VMCOREINFO_FILENAME,
> +                                &info, sizeof(info));
> +    g_assert_cmpint(filesize, ==, sizeof(info));
> +
> +    size = le32_to_cpu(info.size);
> +    paddr = le64_to_cpu(info.paddr);
> +    guest_format = le16_to_cpu(info.guest_format);
> +
> +    g_assert_cmpint(size, ==, 1 * MiB);
> +    g_assert_cmpint(paddr, ==, 0xffffff00);
> +    g_assert_cmpint(guest_format, ==, FW_CFG_VMCOREINFO_FORMAT_ELF);
> +
> +    pc_fw_cfg_uninit(fw_cfg);
> +    qtest_shutdown(qs);
> +}
> +
> +int main(int argc, char **argv)
> +{
> +    const char *arch = qtest_get_arch();
> +
> +    g_test_init(&argc, &argv, NULL);
> +
> +    if (strcmp(arch, "i386") && strcmp(arch, "x86_64")) {
> +        /* skip for non-x86 */
> +        exit(EXIT_SUCCESS);
> +    }
> +
> +    qtest_add_func("vmcoreinfo/basic-write",
> +                   test_vmcoreinfo_write_basic);
> +
> +    return g_test_run();
> +}
> --
> 2.45.2
>

Re: [PATCH v6 2/3] tests/qtest/libqos: add DMA support for writing and reading fw_cfg files

[Fabiano Rosas]

Ani Sinha <anisinha@redhat.com> writes:

> At present, the libqos/fw_cfg.c library does not support the modern DMA
> interface which is required to write to the fw_cfg files. It only uses the IO
> interface. Implement read and write methods based on DMA. This will enable
> developers to add tests that writes to the fw_cfg file(s). The structure of
> the code is taken from edk2 fw_cfg implementation. It has been tested by
> writing a qtest that writes to a fw_cfg file.
>
> Signed-off-by: Ani Sinha <anisinha@redhat.com>

Reviewed-by: Fabiano Rosas <farosas@suse.de>

Re: [PATCH v6 3/3] tests/qtest/vmcoreinfo: add a unit test to exercize basic vmcoreinfo function

[Fabiano Rosas]

Ani Sinha <anisinha@redhat.com> writes:

> A new qtest is written that exercizes the fw-cfg DMA based read and write ops
> to write values into vmcoreinfo fw-cfg file and read them back and verify that
> they are the same.
>
> Signed-off-by: Ani Sinha <anisinha@redhat.com>

Reviewed-by: Fabiano Rosas <farosas@suse.de>

Re: [PATCH v6 0/3] tests/qtest/libqos: add DMA support for writing and reading fw_cfg files

[Fabiano Rosas]

Ani Sinha <anisinha@redhat.com> writes:

> This patchset enables DMA interface support for writing fw-cfg files in
> libqtest. The first patch is just a code refactoring so that fw-cfg
> directory parsing can be part of a separate helper function.
> The second patch is the actual patch that introduces two new apis for
> writing and reading fw-cfg files using DMA interface. The apis are
> tested by writing a new basic qtest for vmcoreinfo device in patch 3.
>
> $ MALLOC_PERTURB_=255  QTEST_QEMU_BINARY=./qemu-system-x86_64  /workspace/qemu-ani/build/tests/qtest/vmcoreinfo-test
> TAP version 13
> # random seed: R02S33ea0ae4568aae69a6191a97e6ea37fc
> 1..1
> # Start of x86_64 tests
> # Start of vmcoreinfo tests
> # starting QEMU: exec ./qemu-system-x86_64 -qtest unix:/tmp/qtest-267380.sock -qtest-log /dev/null -chardev socket,path=/tmp/qtest-267380.qmp,id=char0 -mon chardev=char0,mode=control -display none -audio none -device vmcoreinfo -accel qtest
> ok 1 /x86_64/vmcoreinfo/basic-write
> # End of vmcoreinfo tests
> # End of x86_64 tests
>
> CI pipeline is green with this patch series: https://gitlab.com/anisinha/qemu/-/pipelines/1629670893
>
> checkpatch is clean:
>
> $ ./scripts/checkpatch.pl patches-v6/*
> Checking patches-v6/v6-0000-cover-letter.patch...
> total: 0 errors, 0 warnings, 0 lines checked
>
> patches-v6/v6-0000-cover-letter.patch has no obvious style problems and is ready for submission.
> Checking patches-v6/v6-0001-libqos-fw_cfg-refactor-file-directory-iteraton-to.patch...
> total: 0 errors, 0 warnings, 80 lines checked
>
> patches-v6/v6-0001-libqos-fw_cfg-refactor-file-directory-iteraton-to.patch has no obvious style problems and is ready for submission.
> Checking patches-v6/v6-0002-tests-qtest-libqos-add-DMA-support-for-writing-an.patch...
> total: 0 errors, 0 warnings, 175 lines checked
>
> patches-v6/v6-0002-tests-qtest-libqos-add-DMA-support-for-writing-an.patch has no obvious style problems and is ready for submission.
> Checking patches-v6/v6-0003-tests-qtest-vmcoreinfo-add-a-unit-test-to-exerciz.patch...
> total: 0 errors, 0 warnings, 111 lines checked
>
> patches-v6/v6-0003-tests-qtest-vmcoreinfo-add-a-unit-test-to-exerciz.patch has no obvious style problems and is ready for submission.
>
>
> cc: kraxel@redhat.com
> cc: farosas@suse.de
> cc: lvivier@redhat.com
> cc: pbonzini@redhat.com
> cc: armbru@redhat.com
> cc: philmd@linaro.org
> cc: berrange@redhat.com
> cc: qemu-devel@nongnu.org
> cc: farosas@suse.de

I'll give it the rest of the week and take this series via qtest-next
unless there's objections.