From: Tianyu Lan <Tianyu.Lan@microsoft.com>
Date: Mon, 13 Jun 2022 21:45:53 -0400
Subject: x86/Hyper-V: Add SEV negotiate protocol support in Isolation VM
Git-commit: 49d6a3c062a1026a5ba957c46f3603c372288ab6
Patch-mainline: v5.19-rc3
References: bsc#1190497
Hyper-V Isolation VM current code uses sev_es_ghcb_hv_call()
to read/write MSR via GHCB page and depends on the sev code.
This may cause regression when sev code changes interface
design.
The latest SEV-ES code requires to negotiate GHCB version before
reading/writing MSR via GHCB page and sev_es_ghcb_hv_call() doesn't
work for Hyper-V Isolation VM. Add Hyper-V ghcb related implementation
to decouple SEV and Hyper-V code. Negotiate GHCB version in the
hyperv_init() and use the version to communicate with Hyper-V
in the ghcb hv call function.
Fixes: 2ea29c5abbc2 ("x86/sev: Save the negotiated GHCB version")
Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20220614014553.1915929-1-ltykernel@gmail.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Acked-by: Borislav Petkov <bp@suse.de>
---
arch/x86/hyperv/hv_init.c | 6 +++
arch/x86/hyperv/ivm.c | 84 ++++++++++++++++++++++++++++++++++++++---
arch/x86/include/asm/mshyperv.h | 4 ++
3 files changed, 88 insertions(+), 6 deletions(-)
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index 8b392b6b7b93..3de6d8b53367 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -13,6 +13,7 @@
#include <linux/io.h>
#include <asm/apic.h>
#include <asm/desc.h>
+#include <asm/sev.h>
#include <asm/hypervisor.h>
#include <asm/hyperv-tlfs.h>
#include <asm/mshyperv.h>
@@ -405,6 +406,11 @@ void __init hyperv_init(void)
}
if (hv_isolation_type_snp()) {
+ /* Negotiate GHCB Version. */
+ if (!hv_ghcb_negotiate_protocol())
+ hv_ghcb_terminate(SEV_TERM_SET_GEN,
+ GHCB_SEV_ES_PROT_UNSUPPORTED);
+
hv_ghcb_pg = alloc_percpu(union hv_ghcb *);
if (!hv_ghcb_pg)
goto free_vp_assist_page;
diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index 2b994117581e..1dbcbd9da74d 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -53,6 +53,8 @@ union hv_ghcb {
} hypercall;
} __packed __aligned(HV_HYP_PAGE_SIZE);
+static u16 hv_ghcb_version __ro_after_init;
+
u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size)
{
union hv_ghcb *hv_ghcb;
@@ -96,12 +98,85 @@ u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_size)
return status;
}
+static inline u64 rd_ghcb_msr(void)
+{
+ return __rdmsr(MSR_AMD64_SEV_ES_GHCB);
+}
+
+static inline void wr_ghcb_msr(u64 val)
+{
+ native_wrmsrl(MSR_AMD64_SEV_ES_GHCB, val);
+}
+
+static enum es_result hv_ghcb_hv_call(struct ghcb *ghcb, u64 exit_code,
+ u64 exit_info_1, u64 exit_info_2)
+{
+ /* Fill in protocol and format specifiers */
+ ghcb->protocol_version = hv_ghcb_version;
+ ghcb->ghcb_usage = GHCB_DEFAULT_USAGE;
+
+ ghcb_set_sw_exit_code(ghcb, exit_code);
+ ghcb_set_sw_exit_info_1(ghcb, exit_info_1);
+ ghcb_set_sw_exit_info_2(ghcb, exit_info_2);
+
+ VMGEXIT();
+
+ if (ghcb->save.sw_exit_info_1 & GENMASK_ULL(31, 0))
+ return ES_VMM_ERROR;
+ else
+ return ES_OK;
+}
+
+void hv_ghcb_terminate(unsigned int set, unsigned int reason)
+{
+ u64 val = GHCB_MSR_TERM_REQ;
+
+ /* Tell the hypervisor what went wrong. */
+ val |= GHCB_SEV_TERM_REASON(set, reason);
+
+ /* Request Guest Termination from Hypvervisor */
+ wr_ghcb_msr(val);
+ VMGEXIT();
+
+ while (true)
+ asm volatile("hlt\n" : : : "memory");
+}
+
+bool hv_ghcb_negotiate_protocol(void)
+{
+ u64 ghcb_gpa;
+ u64 val;
+
+ /* Save ghcb page gpa. */
+ ghcb_gpa = rd_ghcb_msr();
+
+ /* Do the GHCB protocol version negotiation */
+ wr_ghcb_msr(GHCB_MSR_SEV_INFO_REQ);
+ VMGEXIT();
+ val = rd_ghcb_msr();
+
+ if (GHCB_MSR_INFO(val) != GHCB_MSR_SEV_INFO_RESP)
+ return false;
+
+ if (GHCB_MSR_PROTO_MAX(val) < GHCB_PROTOCOL_MIN ||
+ GHCB_MSR_PROTO_MIN(val) > GHCB_PROTOCOL_MAX)
+ return false;
+
+ hv_ghcb_version = min_t(size_t, GHCB_MSR_PROTO_MAX(val),
+ GHCB_PROTOCOL_MAX);
+
+ /* Write ghcb page back after negotiating protocol. */
+ wr_ghcb_msr(ghcb_gpa);
+ VMGEXIT();
+
+ return true;
+}
+
void hv_ghcb_msr_write(u64 msr, u64 value)
{
union hv_ghcb *hv_ghcb;
void **ghcb_base;
unsigned long flags;
- struct es_em_ctxt ctxt;
if (!hv_ghcb_pg)
return;
@@ -120,8 +195,7 @@ void hv_ghcb_msr_write(u64 msr, u64 value)
ghcb_set_rax(&hv_ghcb->ghcb, lower_32_bits(value));
ghcb_set_rdx(&hv_ghcb->ghcb, upper_32_bits(value));
- if (sev_es_ghcb_hv_call(&hv_ghcb->ghcb, false, &ctxt,
- SVM_EXIT_MSR, 1, 0))
+ if (hv_ghcb_hv_call(&hv_ghcb->ghcb, SVM_EXIT_MSR, 1, 0))
pr_warn("Fail to write msr via ghcb %llx.\n", msr);
local_irq_restore(flags);
@@ -133,7 +207,6 @@ void hv_ghcb_msr_read(u64 msr, u64 *value)
union hv_ghcb *hv_ghcb;
void **ghcb_base;
unsigned long flags;
- struct es_em_ctxt ctxt;
/* Check size of union hv_ghcb here. */
BUILD_BUG_ON(sizeof(union hv_ghcb) != HV_HYP_PAGE_SIZE);
@@ -152,8 +225,7 @@ void hv_ghcb_msr_read(u64 msr, u64 *value)
}
ghcb_set_rcx(&hv_ghcb->ghcb, msr);
- if (sev_es_ghcb_hv_call(&hv_ghcb->ghcb, false, &ctxt,
- SVM_EXIT_MSR, 0, 0))
+ if (hv_ghcb_hv_call(&hv_ghcb->ghcb, SVM_EXIT_MSR, 0, 0))
pr_warn("Fail to read msr via ghcb %llx.\n", msr);
else
*value = (u64)lower_32_bits(hv_ghcb->ghcb.save.rax)
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index a82f603d4312..61f0c206bff0 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -179,9 +179,13 @@ int hv_set_mem_host_visibility(unsigned long addr, int numpages, bool visible);
#ifdef CONFIG_AMD_MEM_ENCRYPT
void hv_ghcb_msr_write(u64 msr, u64 value);
void hv_ghcb_msr_read(u64 msr, u64 *value);
+bool hv_ghcb_negotiate_protocol(void);
+void hv_ghcb_terminate(unsigned int set, unsigned int reason);
#else
static inline void hv_ghcb_msr_write(u64 msr, u64 value) {}
static inline void hv_ghcb_msr_read(u64 msr, u64 *value) {}
+static inline bool hv_ghcb_negotiate_protocol(void) { return false; }
+static inline void hv_ghcb_terminate(unsigned int set, unsigned int reason) {}
#endif
extern bool hv_isolation_type_snp(void);