From: Tianyu Lan <[email protected]>
Hyper-V Isolation VM code uses sev_es_ghcb_hv_call() to read/write MSR
via ghcb page. The SEV-ES guest should call the sev_es_negotiate_protocol()
to negotiate the GHCB protocol version before establishing the GHCB. Call
sev_es_negotiate_protocol() in the hyperv_init_ghcb().
Signed-off-by: Tianyu Lan <[email protected]>
---
This patch based on the "Add AMD Secure Nested Paging (SEV-SNP) Guest Support"
patchset. https://lore.kernel.org/lkml/[email protected]/
arch/x86/hyperv/hv_init.c | 6 ++++++
arch/x86/include/asm/sev.h | 2 ++
arch/x86/kernel/sev-shared.c | 2 +-
arch/x86/kernel/sev.c | 4 ++--
4 files changed, 11 insertions(+), 3 deletions(-)
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 24f4a06ac46a..a22303fccf02 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -28,6 +28,7 @@
#include <linux/syscore_ops.h>
#include <clocksource/hyperv_timer.h>
#include <linux/highmem.h>
+#include <asm/sev.h>
int hyperv_init_cpuhp;
u64 hv_current_partition_id = ~0ull;
@@ -69,6 +70,11 @@ static int hyperv_init_ghcb(void)
ghcb_base = (void **)this_cpu_ptr(hv_ghcb_pg);
*ghcb_base = ghcb_va;
+ sev_es_negotiate_protocol();
+
+ /* Write ghcb page back after negotiating protocol. */
+ wrmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);
+ VMGEXIT();
return 0;
}
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 7a5934af9d47..fc6b0c526492 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -120,6 +120,8 @@ extern enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,
struct es_em_ctxt *ctxt,
u64 exit_code, u64 exit_info_1,
u64 exit_info_2);
+extern bool sev_es_negotiate_protocol(void);
+
static inline int rmpadjust(unsigned long vaddr, bool rmp_psize, unsigned long attrs)
{
int rc;
diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c
index ce06cb7c8ed0..8b8af5a8d402 100644
--- a/arch/x86/kernel/sev-shared.c
+++ b/arch/x86/kernel/sev-shared.c
@@ -145,7 +145,7 @@ static void snp_register_ghcb_early(unsigned long paddr)
sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_REGISTER);
}
-static bool sev_es_negotiate_protocol(void)
+bool sev_es_negotiate_protocol(void)
{
u64 val;
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 3568b3303314..46c53c4885ee 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -167,12 +167,12 @@ void noinstr __sev_es_ist_exit(void)
this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], *(unsigned long *)ist);
}
-static inline u64 sev_es_rd_ghcb_msr(void)
+inline u64 sev_es_rd_ghcb_msr(void)
{
return __rdmsr(MSR_AMD64_SEV_ES_GHCB);
}
-static __always_inline void sev_es_wr_ghcb_msr(u64 val)
+__always_inline void sev_es_wr_ghcb_msr(u64 val)
{
u32 low, high;
--
2.25.1
On Mon, Feb 07, 2022 at 11:09:28AM -0500, Tianyu Lan wrote:
> From: Tianyu Lan <[email protected]>
>
> Hyper-V Isolation VM code uses sev_es_ghcb_hv_call() to read/write MSR
> via ghcb page. The SEV-ES guest should call the sev_es_negotiate_protocol()
> to negotiate the GHCB protocol version before establishing the GHCB. Call
> sev_es_negotiate_protocol() in the hyperv_init_ghcb().
>
> Signed-off-by: Tianyu Lan <[email protected]>
> ---
> This patch based on the "Add AMD Secure Nested Paging (SEV-SNP) Guest Support"
> patchset. https://lore.kernel.org/lkml/[email protected]/
>
> arch/x86/hyperv/hv_init.c | 6 ++++++
> arch/x86/include/asm/sev.h | 2 ++
> arch/x86/kernel/sev-shared.c | 2 +-
> arch/x86/kernel/sev.c | 4 ++--
> 4 files changed, 11 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index 24f4a06ac46a..a22303fccf02 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -28,6 +28,7 @@
> #include <linux/syscore_ops.h>
> #include <clocksource/hyperv_timer.h>
> #include <linux/highmem.h>
> +#include <asm/sev.h>
>
> int hyperv_init_cpuhp;
> u64 hv_current_partition_id = ~0ull;
> @@ -69,6 +70,11 @@ static int hyperv_init_ghcb(void)
> ghcb_base = (void **)this_cpu_ptr(hv_ghcb_pg);
> *ghcb_base = ghcb_va;
>
> + sev_es_negotiate_protocol();
The return value should be checked, right?
There is no logical connection between this function call and the wrmsrl
below. Is there new information available after calling
sev_es_negotiate_protocol?
> +
> + /* Write ghcb page back after negotiating protocol. */
> + wrmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);
> + VMGEXIT();
> return 0;
> }
>
[...]
> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
> index 3568b3303314..46c53c4885ee 100644
> --- a/arch/x86/kernel/sev.c
> +++ b/arch/x86/kernel/sev.c
> @@ -167,12 +167,12 @@ void noinstr __sev_es_ist_exit(void)
> this_cpu_write(cpu_tss_rw.x86_tss.ist[IST_INDEX_VC], *(unsigned long *)ist);
> }
>
> -static inline u64 sev_es_rd_ghcb_msr(void)
> +inline u64 sev_es_rd_ghcb_msr(void)
> {
> return __rdmsr(MSR_AMD64_SEV_ES_GHCB);
> }
>
> -static __always_inline void sev_es_wr_ghcb_msr(u64 val)
> +__always_inline void sev_es_wr_ghcb_msr(u64 val)
Why are these needed? They are not used anywhere in this patch.
Thanks,
Wei.
> {
> u32 low, high;
>
> --
> 2.25.1
>
Nits:
> Hyper-V Isolation VM code uses sev_es_ghcb_hv_call() to read/write MSR
> via ghcb page. The SEV-ES guest should call the sev_es_negotiate_protocol()
ghcb page -> GHCB page
call the sev_es_negotiate_protocol() -> call sev_es_negotiate_protocol()
(or -- call the sev_es_negotiate_protocol() function)
> to negotiate the GHCB protocol version before establishing the GHCB. Call
> sev_es_negotiate_protocol() in the hyperv_init_ghcb().
in the hyperv_init_ghcb() -> in hyperv_init_ghcb()
(similarly elsewhere).
Andrea