Commit 0fc5deae authored Oct 03, 2019 by Tom Lendacky Committed by Paolo Bonzini Oct 22, 2019

KVM: SVM: Remove unneeded WBINVD and DF_FLUSH when starting SEV guests



Performing a WBINVD and DF_FLUSH are expensive operations. The SEV support
currently performs this WBINVD/DF_FLUSH combination when an SEV guest is
terminated, so there is no need for it to be done before LAUNCH.

However, when the SEV firmware transitions the platform from UNINIT state
to INIT state, all ASIDs will be marked invalid across all threads.
Therefore, as part of transitioning the platform to INIT state, perform a
WBINVD/DF_FLUSH after a successful INIT in the PSP/SEV device driver.
Since the PSP/SEV device driver is x86 only, it can reference and use the
WBINVD related functions directly.

Cc: Gary Hook <gary.hook@amd.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Tested-by: David Rientjes <rientjes@google.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 04f11ef4

arch/x86/kvm/svm.c

+0 −15

Original line number	Diff line number	Diff line
		@@ -6329,21 +6329,6 @@ static int sev_bind_asid(struct kvm kvm, unsigned int handle, int error)
		int asid = sev_get_asid(kvm);
		int ret;

		/*
		* Guard against a DEACTIVATE command before the DF_FLUSH command
		* has completed.
		*/
		mutex_lock(&sev_deactivate_lock);

		wbinvd_on_all_cpus();

		ret = sev_guest_df_flush(error);

		mutex_unlock(&sev_deactivate_lock);

		if (ret)
		return ret;

		data = kzalloc(sizeof(*data), GFP_KERNEL_ACCOUNT);
		if (!data)
		return -ENOMEM;

drivers/crypto/ccp/psp-dev.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -21,6 +21,8 @@
		#include <linux/ccp.h>
		#include <linux/firmware.h>

		#include <asm/smp.h>

		#include "sp-dev.h"
		#include "psp-dev.h"

		@@ -235,6 +237,13 @@ static int __sev_platform_init_locked(int *error)
		return rc;

		psp->sev_state = SEV_STATE_INIT;

		/* Prepare for first SEV guest launch after INIT */
		wbinvd_on_all_cpus();
		rc = __sev_do_cmd_locked(SEV_CMD_DF_FLUSH, NULL, error);
		if (rc)
		return rc;

		dev_dbg(psp->dev, "SEV firmware initialized\n");

		return rc;

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