KVM Archive on lore.kernel.org
 help / color / Atom feed
From: Aaron Lewis <aaronlewis@google.com>
To: jmattson@google.com, kvm@vger.kernel.org
Cc: Aaron Lewis <aaronlewis@google.com>
Subject: [PATCH] KVM: CPUID: Add new features to the guest's CPUID
Date: Mon, 15 Jul 2019 14:03:16 -0700
Message-ID: <20190715210316.25569-1-aaronlewis@google.com> (raw)

Add features X86_FEATURE_FDP_EXCPTN_ONLY and X86_FEATURE_ZERO_FCS_FDS to the
mask for CPUID.(EAX=07H,ECX=0H):EBX.  Doing this will ensure the guest's CPUID
for these bits match the host, rather than the guest being blindly set to 0.

This is important as these are actually defeature bits, which means that
a 0 indicates the presence of a feature and a 1 indicates the absence of
a feature.  since these features cannot be emulated, kvm should not
claim the existence of a feature that isn't present on the host.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
---
 arch/x86/kvm/cpuid.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index ead681210306..64c3fad068e1 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -353,7 +353,8 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry, int index)
 		F(BMI2) | F(ERMS) | f_invpcid | F(RTM) | f_mpx | F(RDSEED) |
 		F(ADX) | F(SMAP) | F(AVX512IFMA) | F(AVX512F) | F(AVX512PF) |
 		F(AVX512ER) | F(AVX512CD) | F(CLFLUSHOPT) | F(CLWB) | F(AVX512DQ) |
-		F(SHA_NI) | F(AVX512BW) | F(AVX512VL) | f_intel_pt;
+		F(SHA_NI) | F(AVX512BW) | F(AVX512VL) | f_intel_pt |
+		F(FDP_EXCPTN_ONLY) | F(ZERO_FCS_FDS);
 
 	/* cpuid 7.0.ecx*/
 	const u32 kvm_cpuid_7_0_ecx_x86_features =
-- 
2.22.0.510.g264f2c817a-goog


             reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-15 21:03 Aaron Lewis [this message]
2019-07-22 14:51 ` Aaron Lewis
2019-07-23 21:42 ` Krish Sadhukhan
2019-08-21 16:17   ` Aaron Lewis

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190715210316.25569-1-aaronlewis@google.com \
    --to=aaronlewis@google.com \
    --cc=jmattson@google.com \
    --cc=kvm@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

KVM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kvm/0 kvm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kvm kvm/ https://lore.kernel.org/kvm \
		kvm@vger.kernel.org
	public-inbox-index kvm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.kvm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git