[PATCH v4 03/10] x86/hyper-v: make hv_do_hypercall() inline

Vitaly Kuznetsov
2017-05-24T12:07:12Z

We have only three call sites for hv_do_hypercall() and we're going to
change HVCALL_SIGNAL_EVENT to doing fast hypercall so we can inline this
function for optimization.

Hyper-V top level functional specification states that r9-r11 registers
and flags may be clobbered by the hypervisor during hypercall and with
inlining this is somewhat important, add the clobbers.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Tested-by: Simon Xiao <sixiao@microsoft.com>
Tested-by: Srikanth Myakam <v-srm@microsoft.com>
---
Change since v3:
- Force stack frame in hv_do_hypercall() [Andy Lutomirski]
---
arch/x86/hyperv/hv_init.c | 54 ++++-------------------------------------
arch/x86/include/asm/mshyperv.h | 44 +++++++++++++++++++++++++++++++++
drivers/hv/connection.c | 2 ++
include/linux/hyperv.h | 1 -
4 files changed, 51 insertions(+), 50 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 5b882cc..691603e 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -75,7 +75,8 @@ static struct clocksource hyperv_cs_msr = {
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};

-static void *hypercall_pg;
+void *hv_hypercall_pg;
+EXPORT_SYMBOL_GPL(hv_hypercall_pg);
struct clocksource *hyperv_cs;
EXPORT_SYMBOL_GPL(hyperv_cs);

@@ -102,15 +103,15 @@ void hyperv_init(void)
guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);

- hypercall_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
- if (hypercall_pg == NULL) {
+ hv_hypercall_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
+ if (hv_hypercall_pg == NULL) {
wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
return;
}

rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
hypercall_msr.enable = 1;
- hypercall_msr.guest_physical_address = vmalloc_to_pfn(hypercall_pg);
+ hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

/*
@@ -170,51 +171,6 @@ void hyperv_cleanup(void)
}
EXPORT_SYMBOL_GPL(hyperv_cleanup);

-/*
- * hv_do_hypercall- Invoke the specified hypercall
- */
-u64 hv_do_hypercall(u64 control, void *input, void *output)
-{
- u64 input_address = (input) ? virt_to_phys(input) : 0;
- u64 output_address = (output) ? virt_to_phys(output) : 0;
-#ifdef CONFIG_X86_64
- u64 hv_status = 0;
-
- if (!hypercall_pg)
- return (u64)ULLONG_MAX;
-
- __asm__ __volatile__("mov %0, %%r8" : : "r" (output_address) : "r8");
- __asm__ __volatile__("call *%3" : "=a" (hv_status) :
- "c" (control), "d" (input_address),
- "m" (hypercall_pg));
-
- return hv_status;
-
-#else
-
- u32 control_hi = control >> 32;
- u32 control_lo = control & 0xFFFFFFFF;
- u32 hv_status_hi = 1;
- u32 hv_status_lo = 1;
- u32 input_address_hi = input_address >> 32;
- u32 input_address_lo = input_address & 0xFFFFFFFF;
- u32 output_address_hi = output_address >> 32;
- u32 output_address_lo = output_address & 0xFFFFFFFF;
-
- if (!hypercall_pg)
- return (u64)ULLONG_MAX;
-
- __asm__ __volatile__ ("call *%8" : "=d"(hv_status_hi),
- "=a"(hv_status_lo) : "d" (control_hi),
- "a" (control_lo), "b" (input_address_hi),
- "c" (input_address_lo), "D"(output_address_hi),
- "S"(output_address_lo), "m" (hypercall_pg));
-
- return hv_status_lo | ((u64)hv_status_hi << 32);
-#endif /* !x86_64 */
-}
-EXPORT_SYMBOL_GPL(hv_do_hypercall);
-
void hyperv_report_panic(struct pt_regs *regs)
{
static bool panic_reported;
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index d42b6eb..cbbf7db 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -172,6 +172,50 @@ void hv_remove_crash_handler(void);

#if IS_ENABLED(CONFIG_HYPERV)
extern struct clocksource *hyperv_cs;
+extern void *hv_hypercall_pg;
+
+static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
+{
+ u64 input_address = (input) ? virt_to_phys(input) : 0;
+ u64 output_address = (output) ? virt_to_phys(output) : 0;
+ register void *__sp asm(_ASM_SP);
+#ifdef CONFIG_X86_64
+ u64 hv_status;
+
+ if (!hv_hypercall_pg)
+ return (u64)ULLONG_MAX;
+
+ __asm__ __volatile__("mov %4, %%r8\n"
+ "call *%5"
+ : "=a" (hv_status), "+r" (__sp),
+ "+c" (control), "+d" (input_address)
+ : "r" (output_address), "m" (hv_hypercall_pg)
+ : "cc", "memory", "r8", "r9", "r10", "r11");
+
+ return hv_status;
+
+#else
+ u32 control_hi = control >> 32;
+ u32 control_lo = control & 0xFFFFFFFF;
+ u32 input_address_hi = input_address >> 32;
+ u32 input_address_lo = input_address & 0xFFFFFFFF;
+ u32 output_address_hi = output_address >> 32;
+ u32 output_address_lo = output_address & 0xFFFFFFFF;
+
+ if (!hv_hypercall_pg)
+ return (u64)ULLONG_MAX;
+
+ __asm__ __volatile__("call *%7"
+ : "+a" (control_lo), "+d" (control_hi),
+ "+c" (input_address_lo), "+r" (__sp)
+ : "b" (input_address_hi),
+ "D"(output_address_hi), "S"(output_address_lo),
+ "m" (hv_hypercall_pg)
+ : "cc", "memory");
+
+ return control_lo | ((u64)control_hi << 32);
+#endif /* !x86_64 */
+}

void hyperv_init(void);
void hyperv_report_panic(struct pt_regs *regs);
diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
index c2d74ee..4a0a9f6 100644
--- a/drivers/hv/connection.c
+++ b/drivers/hv/connection.c
@@ -32,6 +32,8 @@
#include <linux/hyperv.h>
#include <linux/export.h>
#include <asm/hyperv.h>
+#include <asm/mshyperv.h>
+
#include "hyperv_vmbus.h"

diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index e09fc82..d1ae02d 100644
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -1188,7 +1188,6 @@ int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj,
bool fb_overlap_ok);
void vmbus_free_mmio(resource_size_t start, resource_size_t size);
int vmbus_cpu_number_to_vp_number(int cpu_number);
-u64 hv_do_hypercall(u64 control, void *input, void *output);

/*
* GUID definitions of various offer types - services offered to the guest.
--
2.9.4