[PATCH V2 04/14] x86/HV: Add new hvcall guest address host visibility support

Tianyu Lan
2021-08-04T18:45:49Z

Add new hvcall guest address host visibility support to mark
memory visible to host. Override x86_set_memory_enc static
call with hv hook to mark memory visible to host via set_
memory_decrypted().

Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
Change since v1:
* Use new staic call x86_set_memory_enc to avoid add Hyper-V
specific check in the set_memory code.

Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
---
arch/x86/hyperv/Makefile | 2 +-
arch/x86/hyperv/hv_init.c | 6 ++
arch/x86/hyperv/ivm.c | 114 +++++++++++++++++++++++++++++
arch/x86/include/asm/hyperv-tlfs.h | 20 +++++
arch/x86/include/asm/mshyperv.h | 4 +-
include/asm-generic/hyperv-tlfs.h | 1 +
6 files changed, 145 insertions(+), 2 deletions(-)
create mode 100644 arch/x86/hyperv/ivm.c

diff --git a/arch/x86/hyperv/Makefile b/arch/x86/hyperv/Makefile
index 48e2c51464e8..5d2de10809ae 100644
--- a/arch/x86/hyperv/Makefile
+++ b/arch/x86/hyperv/Makefile
@@ -1,5 +1,5 @@
# SPDX-License-Identifier: GPL-2.0-only
-obj-y := hv_init.o mmu.o nested.o irqdomain.o
+obj-y := hv_init.o mmu.o nested.o irqdomain.o ivm.o
obj-$(CONFIG_X86_64) += hv_apic.o hv_proc.o

ifdef CONFIG_X86_64
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 247df301491f..57962d407484 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -17,6 +17,7 @@
#include <asm/hyperv-tlfs.h>
#include <asm/mshyperv.h>
#include <asm/idtentry.h>
+#include <asm/set_memory.h>
#include <linux/kexec.h>
#include <linux/version.h>
#include <linux/vmalloc.h>
@@ -29,6 +30,7 @@
#include <linux/syscore_ops.h>
#include <clocksource/hyperv_timer.h>
#include <linux/highmem.h>
+#include <linux/static_call.h>

int hyperv_init_cpuhp;
u64 hv_current_partition_id = ~0ull;
@@ -450,6 +452,10 @@ void __init hyperv_init(void)

/* Query the VMs extended capability once, so that it can be cached. */
hv_query_ext_cap(0);
+
+ if (hv_is_isolation_supported())
+ static_call_update(x86_set_memory_enc, hv_set_mem_enc);
+
return;

clean_guest_os_id:
diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
new file mode 100644
index 000000000000..6d130ba03f41
--- /dev/null
+++ b/arch/x86/hyperv/ivm.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Hyper-V Isolation VM interface with paravisor and hypervisor
+ *
+ * Author:
+ * Tianyu Lan <Tianyu.Lan@microsoft.com>
+ */
+
+#include <linux/hyperv.h>
+#include <linux/types.h>
+#include <linux/bitfield.h>
+#include <linux/slab.h>
+#include <asm/io.h>
+#include <asm/mshyperv.h>
+
+/*
+ * hv_mark_gpa_visibility - Set pages visible to host via hvcall.
+ *
+ * In Isolation VM, all guest memory is encripted from host and guest
+ * needs to set memory visible to host via hvcall before sharing memory
+ * with host.
+ */
+int hv_mark_gpa_visibility(u16 count, const u64 pfn[],
+ enum hv_mem_host_visibility visibility)
+{
+ struct hv_gpa_range_for_visibility **input_pcpu, *input;
+ u16 pages_processed;
+ u64 hv_status;
+ unsigned long flags;
+
+ /* no-op if partition isolation is not enabled */
+ if (!hv_is_isolation_supported())
+ return 0;
+
+ if (count > HV_MAX_MODIFY_GPA_REP_COUNT) {
+ pr_err("Hyper-V: GPA count:%d exceeds supported:%lu\n", count,
+ HV_MAX_MODIFY_GPA_REP_COUNT);
+ return -EINVAL;
+ }
+
+ local_irq_save(flags);
+ input_pcpu = (struct hv_gpa_range_for_visibility **)
+ this_cpu_ptr(hyperv_pcpu_input_arg);
+ input = *input_pcpu;
+ if (unlikely(!input)) {
+ local_irq_restore(flags);
+ return -EINVAL;
+ }
+
+ input->partition_id = HV_PARTITION_ID_SELF;
+ input->host_visibility = visibility;
+ input->reserved0 = 0;
+ input->reserved1 = 0;
+ memcpy((void *)input->gpa_page_list, pfn, count * sizeof(*pfn));
+ hv_status = hv_do_rep_hypercall(
+ HVCALL_MODIFY_SPARSE_GPA_PAGE_HOST_VISIBILITY, count,
+ 0, input, &pages_processed);
+ local_irq_restore(flags);
+
+ if (!(hv_status & HV_HYPERCALL_RESULT_MASK))
+ return 0;
+
+ return hv_status & HV_HYPERCALL_RESULT_MASK;
+}
+EXPORT_SYMBOL(hv_mark_gpa_visibility);
+
+/*
+ * hv_set_mem_host_visibility - Set specified memory visible to host.
+ *
+ * In Isolation VM, all guest memory is encrypted from host and guest
+ * needs to set memory visible to host via hvcall before sharing memory
+ * with host. This function works as wrap of hv_mark_gpa_visibility()
+ * with memory base and size.
+ */
+static int hv_set_mem_host_visibility(void *kbuffer, int pagecount,
+ enum hv_mem_host_visibility visibility)
+{
+ u64 *pfn_array;
+ int ret = 0;
+ int i, pfn;
+
+ if (!hv_is_isolation_supported() || !ms_hyperv.ghcb_base)
+ return 0;
+
+ pfn_array = kzalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
+ if (!pfn_array)
+ return -ENOMEM;
+
+ for (i = 0, pfn = 0; i < pagecount; i++) {
+ pfn_array[pfn] = virt_to_hvpfn(kbuffer + i * HV_HYP_PAGE_SIZE);
+ pfn++;
+
+ if (pfn == HV_MAX_MODIFY_GPA_REP_COUNT || i == pagecount - 1) {
+ ret |= hv_mark_gpa_visibility(pfn, pfn_array,
+ visibility);
+ pfn = 0;
+
+ if (ret)
+ goto err_free_pfn_array;
+ }
+ }
+
+ err_free_pfn_array:
+ kfree(pfn_array);
+ return ret;
+}
+
+int hv_set_mem_enc(unsigned long addr, int numpages, bool enc)
+{
+ enum hv_mem_host_visibility visibility = enc ? VMBUS_PAGE_NOT_VISIBLE :
+ VMBUS_PAGE_VISIBLE_READ_WRITE;
+
+ return hv_set_mem_host_visibility((void *)addr, numpages, visibility);
+}
diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index f1366ce609e3..1b3e80bcca5b 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h
@@ -276,6 +276,13 @@ enum hv_isolation_type {
#define HV_X64_MSR_TIME_REF_COUNT HV_REGISTER_TIME_REF_COUNT
#define HV_X64_MSR_REFERENCE_TSC HV_REGISTER_REFERENCE_TSC

+/* Hyper-V memory host visibility */
+enum hv_mem_host_visibility {
+ VMBUS_PAGE_NOT_VISIBLE = 0,
+ VMBUS_PAGE_VISIBLE_READ_ONLY = 1,
+ VMBUS_PAGE_VISIBLE_READ_WRITE = 3
+};
+
/*
* Declare the MSR used to setup pages used to communicate with the hypervisor.
*/
@@ -578,4 +585,17 @@ enum hv_interrupt_type {

#include <asm-generic/hyperv-tlfs.h>

+/* All input parameters should be in single page. */
+#define HV_MAX_MODIFY_GPA_REP_COUNT \
+ ((PAGE_SIZE / sizeof(u64)) - 2)
+
+/* HvCallModifySparseGpaPageHostVisibility hypercall */
+struct hv_gpa_range_for_visibility {
+ u64 partition_id;
+ u32 host_visibility:2;
+ u32 reserved0:30;
+ u32 reserved1;
+ u64 gpa_page_list[HV_MAX_MODIFY_GPA_REP_COUNT];
+} __packed;
+
#endif
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index 6627cfd2bfba..33f0e95c9b76 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -190,7 +190,9 @@ struct irq_domain *hv_create_pci_msi_domain(void);
int hv_map_ioapic_interrupt(int ioapic_id, bool level, int vcpu, int vector,
struct hv_interrupt_entry *entry);
int hv_unmap_ioapic_interrupt(int ioapic_id, struct hv_interrupt_entry *entry);
-
+int hv_mark_gpa_visibility(u16 count, const u64 pfn[],
+ enum hv_mem_host_visibility visibility);
+int hv_set_mem_enc(unsigned long addr, int numpages, bool enc);
#else /* CONFIG_HYPERV */
static inline void hyperv_init(void) {}
static inline void hyperv_setup_mmu_ops(void) {}
diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index 56348a541c50..8ed6733d5146 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h
@@ -158,6 +158,7 @@ struct ms_hyperv_tsc_page {
#define HVCALL_RETARGET_INTERRUPT 0x007e
#define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_SPACE 0x00af
#define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_LIST 0x00b0
+#define HVCALL_MODIFY_SPARSE_GPA_PAGE_HOST_VISIBILITY 0x00db

/* Extended hypercalls */
#define HV_EXT_CALL_QUERY_CAPABILITIES 0x8001
--
2.25.1