The following commit has been merged into the x86/sev branch of tip: Commit-ID: 007faec014cb5d26983c1f86fd08c6539b41392e Gitweb: https://git.kernel.org/tip/007faec014cb5d26983c1f86fd08c6539b41392e Author: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx> AuthorDate: Mon, 25 Oct 2021 08:21:10 -04:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Mon, 25 Oct 2021 18:11:42 +02:00 x86/sev: Expose sev_es_ghcb_hv_call() for use by HyperV Hyper-V needs to issue the GHCB HV call in order to read/write MSRs in Isolation VMs. For that, expose sev_es_ghcb_hv_call(). The Hyper-V Isolation VMs are unenlightened guests and run a paravisor at VMPL0 for communicating. GHCB pages are being allocated and set up by that paravisor. Linux gets the GHCB page's physical address via MSR_AMD64_SEV_ES_GHCB from the paravisor and should not change it. Add a @set_ghcb_msr parameter to sev_es_ghcb_hv_call() to control whether the function should set the GHCB's address prior to the call or not and export that function for use by HyperV. [ bp: - Massage commit message - add a struct ghcb forward declaration to fix randconfig builds. ] Signed-off-by: Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20211025122116.264793-6-ltykernel@xxxxxxxxx --- arch/x86/include/asm/sev.h | 6 ++++++ arch/x86/kernel/sev-shared.c | 25 ++++++++++++++++--------- arch/x86/kernel/sev.c | 13 +++++++------ 3 files changed, 29 insertions(+), 15 deletions(-) diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index fa5cd05..ec060c4 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -53,6 +53,7 @@ static inline u64 lower_bits(u64 val, unsigned int bits) struct real_mode_header; enum stack_type; +struct ghcb; /* Early IDT entry points for #VC handler */ extern void vc_no_ghcb(void); @@ -81,6 +82,11 @@ static __always_inline void sev_es_nmi_complete(void) __sev_es_nmi_complete(); } extern int __init sev_es_efi_map_ghcbs(pgd_t *pgd); +extern enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, + bool set_ghcb_msr, + struct es_em_ctxt *ctxt, + u64 exit_code, u64 exit_info_1, + u64 exit_info_2); #else static inline void sev_es_ist_enter(struct pt_regs *regs) { } static inline void sev_es_ist_exit(void) { } diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index 4579c38..0aacd60 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -125,10 +125,9 @@ static enum es_result verify_exception_info(struct ghcb *ghcb, struct es_em_ctxt return ES_VMM_ERROR; } -static 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) +enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, bool set_ghcb_msr, + struct es_em_ctxt *ctxt, u64 exit_code, + u64 exit_info_1, u64 exit_info_2) { /* Fill in protocol and format specifiers */ ghcb->protocol_version = GHCB_PROTOCOL_MAX; @@ -138,7 +137,14 @@ static enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb, ghcb_set_sw_exit_info_1(ghcb, exit_info_1); ghcb_set_sw_exit_info_2(ghcb, exit_info_2); - sev_es_wr_ghcb_msr(__pa(ghcb)); + /* + * Hyper-V unenlightened guests use a paravisor for communicating and + * GHCB pages are being allocated and set up by that paravisor. Linux + * should not change the GHCB page's physical address. + */ + if (set_ghcb_msr) + sev_es_wr_ghcb_msr(__pa(ghcb)); + VMGEXIT(); return verify_exception_info(ghcb, ctxt); @@ -418,7 +424,7 @@ static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt) */ sw_scratch = __pa(ghcb) + offsetof(struct ghcb, shared_buffer); ghcb_set_sw_scratch(ghcb, sw_scratch); - ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO, + ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_IOIO, exit_info_1, exit_info_2); if (ret != ES_OK) return ret; @@ -460,7 +466,8 @@ static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt) ghcb_set_rax(ghcb, rax); - ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO, exit_info_1, 0); + ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, + SVM_EXIT_IOIO, exit_info_1, 0); if (ret != ES_OK) return ret; @@ -491,7 +498,7 @@ static enum es_result vc_handle_cpuid(struct ghcb *ghcb, /* xgetbv will cause #GP - use reset value for xcr0 */ ghcb_set_xcr0(ghcb, 1); - ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_CPUID, 0, 0); + ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_CPUID, 0, 0); if (ret != ES_OK) return ret; @@ -516,7 +523,7 @@ static enum es_result vc_handle_rdtsc(struct ghcb *ghcb, bool rdtscp = (exit_code == SVM_EXIT_RDTSCP); enum es_result ret; - ret = sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, 0, 0); + ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, exit_code, 0, 0); if (ret != ES_OK) return ret; diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 2de1f36..113d3ae 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -648,7 +648,8 @@ static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt) ghcb_set_rdx(ghcb, regs->dx); } - ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_MSR, exit_info_1, 0); + ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_MSR, + exit_info_1, 0); if ((ret == ES_OK) && (!exit_info_1)) { regs->ax = ghcb->save.rax; @@ -867,7 +868,7 @@ static enum es_result vc_do_mmio(struct ghcb *ghcb, struct es_em_ctxt *ctxt, ghcb_set_sw_scratch(ghcb, ghcb_pa + offsetof(struct ghcb, shared_buffer)); - return sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, exit_info_1, exit_info_2); + return sev_es_ghcb_hv_call(ghcb, true, ctxt, exit_code, exit_info_1, exit_info_2); } static enum es_result vc_handle_mmio_twobyte_ops(struct ghcb *ghcb, @@ -1117,7 +1118,7 @@ static enum es_result vc_handle_dr7_write(struct ghcb *ghcb, /* Using a value of 0 for ExitInfo1 means RAX holds the value */ ghcb_set_rax(ghcb, val); - ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_WRITE_DR7, 0, 0); + ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_WRITE_DR7, 0, 0); if (ret != ES_OK) return ret; @@ -1147,7 +1148,7 @@ static enum es_result vc_handle_dr7_read(struct ghcb *ghcb, static enum es_result vc_handle_wbinvd(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { - return sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_WBINVD, 0, 0); + return sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_WBINVD, 0, 0); } static enum es_result vc_handle_rdpmc(struct ghcb *ghcb, struct es_em_ctxt *ctxt) @@ -1156,7 +1157,7 @@ static enum es_result vc_handle_rdpmc(struct ghcb *ghcb, struct es_em_ctxt *ctxt ghcb_set_rcx(ghcb, ctxt->regs->cx); - ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_RDPMC, 0, 0); + ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_RDPMC, 0, 0); if (ret != ES_OK) return ret; @@ -1197,7 +1198,7 @@ static enum es_result vc_handle_vmmcall(struct ghcb *ghcb, if (x86_platform.hyper.sev_es_hcall_prepare) x86_platform.hyper.sev_es_hcall_prepare(ghcb, ctxt->regs); - ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_VMMCALL, 0, 0); + ret = sev_es_ghcb_hv_call(ghcb, true, ctxt, SVM_EXIT_VMMCALL, 0, 0); if (ret != ES_OK) return ret;
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