From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
Juergen Gross <jgross@suse.com>, Deep Shah <sdeep@vmware.com>,
VMware Inc <pv-drivers@vmware.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>
Cc: Peter H Anvin <hpa@zytor.com>,
Dave Hansen <dave.hansen@intel.com>,
Tony Luck <tony.luck@intel.com>,
Dan Williams <dan.j.williams@intel.com>,
Andi Kleen <ak@linux.intel.com>,
Kirill Shutemov <kirill.shutemov@linux.intel.com>,
Sean Christopherson <seanjc@google.com>,
Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
linux-kernel@vger.kernel.org
Subject: [PATCH v7 10/12] x86/tdx: Add MSR support for TDX guest
Date: Thu, 16 Sep 2021 11:35:48 -0700 [thread overview]
Message-ID: <20210916183550.15349-11-sathyanarayanan.kuppuswamy@linux.intel.com> (raw)
In-Reply-To: <20210916183550.15349-1-sathyanarayanan.kuppuswamy@linux.intel.com>
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Operations on context-switched MSRs can be run natively. The rest of
MSRs should be handled through TDVMCALLs.
TDVMCALL[Instruction.RDMSR] and TDVMCALL[Instruction.WRMSR] provide
MSR oprations.
RDMSR and WRMSR specification details can be found in
Guest-Host-Communication Interface (GHCI) for Intel Trust Domain
Extensions (Intel TDX) specification, sec 3.10, 3.11.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
---
Changes since v6:
* None
Changes since v5:
* Renamed "tdg" prefix with "tdx".
* Added comments for _tdx_hypercall() usage in MSR read/write functions.
Change since v4:
* Removed You usage from commit log.
Changes since v3:
* None
arch/x86/kernel/tdx.c | 77 +++++++++++++++++++++++++++++++++++++++++--
1 file changed, 75 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c
index ec1008cc42d9..5c52dde4a5fd 100644
--- a/arch/x86/kernel/tdx.c
+++ b/arch/x86/kernel/tdx.c
@@ -91,6 +91,65 @@ static __cpuidle void tdx_safe_halt(void)
_tdx_halt(irq_disabled, do_sti);
}
+static bool tdx_is_context_switched_msr(unsigned int msr)
+{
+ switch (msr) {
+ case MSR_EFER:
+ case MSR_IA32_CR_PAT:
+ case MSR_FS_BASE:
+ case MSR_GS_BASE:
+ case MSR_KERNEL_GS_BASE:
+ case MSR_IA32_SYSENTER_CS:
+ case MSR_IA32_SYSENTER_EIP:
+ case MSR_IA32_SYSENTER_ESP:
+ case MSR_STAR:
+ case MSR_LSTAR:
+ case MSR_SYSCALL_MASK:
+ case MSR_IA32_XSS:
+ case MSR_TSC_AUX:
+ case MSR_IA32_BNDCFGS:
+ return true;
+ }
+ return false;
+}
+
+static u64 tdx_read_msr_safe(unsigned int msr, int *err)
+{
+ struct tdx_hypercall_output out = {0};
+ u64 ret;
+
+ WARN_ON_ONCE(tdx_is_context_switched_msr(msr));
+
+ /*
+ * Emulate the MSR read via hypercall. More info about ABI
+ * can be found in TDX Guest-Host-Communication Interface
+ * (GHCI), sec 3.10.
+ */
+ ret = _tdx_hypercall(EXIT_REASON_MSR_READ, msr, 0, 0, 0, &out);
+
+ *err = ret ? -EIO : 0;
+
+ return out.r11;
+}
+
+static int tdx_write_msr_safe(unsigned int msr, unsigned int low,
+ unsigned int high)
+{
+ u64 ret;
+
+ WARN_ON_ONCE(tdx_is_context_switched_msr(msr));
+
+ /*
+ * Emulate the MSR write via hypercall. More info about ABI
+ * can be found in TDX Guest-Host-Communication Interface
+ * (GHCI) sec 3.11.
+ */
+ ret = _tdx_hypercall(EXIT_REASON_MSR_WRITE, msr, (u64)high << 32 | low,
+ 0, 0, NULL);
+
+ return ret ? -EIO : 0;
+}
+
unsigned long tdx_get_ve_info(struct ve_info *ve)
{
struct tdx_module_output out = {0};
@@ -117,19 +176,33 @@ unsigned long tdx_get_ve_info(struct ve_info *ve)
int tdx_handle_virtualization_exception(struct pt_regs *regs,
struct ve_info *ve)
{
+ unsigned long val;
+ int ret = 0;
+
switch (ve->exit_reason) {
case EXIT_REASON_HLT:
tdx_halt();
break;
+ case EXIT_REASON_MSR_READ:
+ val = tdx_read_msr_safe(regs->cx, (unsigned int *)&ret);
+ if (!ret) {
+ regs->ax = (u32)val;
+ regs->dx = val >> 32;
+ }
+ break;
+ case EXIT_REASON_MSR_WRITE:
+ ret = tdx_write_msr_safe(regs->cx, regs->ax, regs->dx);
+ break;
default:
pr_warn("Unexpected #VE: %lld\n", ve->exit_reason);
return -EFAULT;
}
/* After successful #VE handling, move the IP */
- regs->ip += ve->instr_len;
+ if (!ret)
+ regs->ip += ve->instr_len;
- return 0;
+ return ret;
}
void __init tdx_early_init(void)
--
2.25.1
next prev parent reply other threads:[~2021-09-16 18:37 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-16 18:35 [PATCH v7 00/12] Add TDX Guest Support (Initial support) Kuppuswamy Sathyanarayanan
2021-09-16 18:35 ` [PATCH v7 01/12] x86/tdx: Add Intel ARCH support to cc_platform_has() Kuppuswamy Sathyanarayanan
2021-09-16 18:44 ` Dave Hansen
2021-09-16 19:06 ` Borislav Petkov
2021-09-16 19:57 ` Dave Hansen
2021-09-17 16:57 ` Borislav Petkov
2021-09-28 11:11 ` Borislav Petkov
2021-09-16 18:35 ` [PATCH v7 02/12] x86/paravirt: Move halt paravirt calls under CONFIG_PARAVIRT Kuppuswamy Sathyanarayanan
2021-09-16 18:35 ` [PATCH v7 03/12] x86/tdx: Introduce INTEL_TDX_GUEST config option Kuppuswamy Sathyanarayanan
2021-09-16 18:35 ` [PATCH v7 04/12] x86/cpufeatures: Add TDX Guest CPU feature Kuppuswamy Sathyanarayanan
2021-09-23 10:02 ` Borislav Petkov
2021-09-23 14:10 ` Kuppuswamy, Sathyanarayanan
2021-09-23 14:16 ` Borislav Petkov
2021-09-23 14:20 ` Kuppuswamy, Sathyanarayanan
2021-09-16 18:35 ` [PATCH v7 05/12] x86/tdx: Add TDX guest support to intel_cc_platform_has() Kuppuswamy Sathyanarayanan
2021-09-23 10:36 ` Borislav Petkov
2021-09-23 14:10 ` Kuppuswamy, Sathyanarayanan
2021-09-16 18:35 ` [PATCH v7 06/12] x86/tdx: Add __tdx_module_call() and __tdx_hypercall() helper functions Kuppuswamy Sathyanarayanan
2021-09-16 18:35 ` [PATCH v7 07/12] x86/traps: Add #VE support for TDX guest Kuppuswamy Sathyanarayanan
2021-09-16 18:35 ` [PATCH v7 08/12] x86/tdx: Add HLT " Kuppuswamy Sathyanarayanan
2021-09-23 18:09 ` Borislav Petkov
2021-09-23 19:33 ` Kuppuswamy, Sathyanarayanan
2021-09-24 20:00 ` Kuppuswamy, Sathyanarayanan
2021-09-16 18:35 ` [PATCH v7 09/12] x86/tdx: Wire up KVM hypercalls Kuppuswamy Sathyanarayanan
2021-09-16 18:35 ` Kuppuswamy Sathyanarayanan [this message]
2021-09-16 18:35 ` [PATCH v7 11/12] x86/tdx: Don't write CSTAR MSR on Intel Kuppuswamy Sathyanarayanan
2021-09-16 18:35 ` [PATCH v7 12/12] x86/tdx: Handle CPUID via #VE Kuppuswamy Sathyanarayanan
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